According to the USDA, “the combined value of production from broilers, eggs, turkeys, and the value of sales from chickens in 2011 was $35.6 billion . . . . Of the combined total, 65 percent was from broilers, 21 percent from eggs, 14 percent from turkeys, and less than 1 percent from chickens.” (USDA, National Agricultural Statistics Service “Poultry—Production and Value 2011 Summary” (April 2012)) According to the US EPA the composition of solid manure from pullets and laying hens in layer cages can range in dry matter between 20% and 60% and semi-solid manure contains 12 to 20% solids. (US EPA| Ag 101| Poultry Production, www.epa.gov/oecaagct/ag101/printpoultry.html). Poultry manure is typically used in surface applications to croplands.
Within the United States, pork production is a major agricultural enterprise; specifically, a gross income of roughly $16 billion resulted from the sale of 116 million pigs in 2008. In general, pigs weighing 21 to 100 kg generate 0.39 to 0.45 kg of waste per day per pig on a dry matter basis. Swine manure is usually disposed of by storage in lagoons. This process has significant negative environmental impacts, particularly with respect to surface water and groundwater quality as well as air quality, which is affected by odors and gaseous emissions.
Dairy and beef production are similarly important components of U.S. agricultural efforts. Removal or treatment of animal waste is analogously a key consideration as the number of cows raised in the U.S. trends upwards.
To improve the ultimate processing of beef, dairy, poultry, sheep and swine manure, researchers have developed methods to convert manure to gas and/or oil. Collection of manure is easier in confined animal feeding operations, due in part to bulk processing of waste, as well as the controlled diet of the animals. Bio-oil produced from animal waste is an energy-dense crude oil that is similar to petroleum extracts. By-products of bio-oil produced from animal waste include an aqueous phase and a solid phase; uses for both by-products have been identified in the art.
Petroleum-based products, such as adhesives, are used in pavement construction as asphalt binders, adhesion promoters, asphalt extenders and asphalt concrete. In addition they are used in roofing, soil stabilization, crack and joint sealing and as flooring adhesives.
The U.S. asphalt market is valued at approximately $11.7 billion/year. Asphalt supplies are shrinking, while the demand for it is increasing rapidly. As the price of asphalt increases, the demand for alternative and renewable resources increases.
The trend toward sustainable pavements has led the pavement industry to emphasize use of recycled materials, including rubber from tires and fly ash as well as reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in pavement construction. Use of these recycled products reduces the environmental liability of RAP and RAS and further reduces the amount of virgin asphalt used in pavement construction. In the U.S., about 100 million tons of RAP and 11 million tons of RAS are produced annually. Because asphalt in both RAP and RAS is much stiffer than virgin asphalt, inclusion of RAP and/or RAS lead to a significant increase in the stiffness of the resulting recycled-asphalt mixture. Stiff asphalt mixtures have been shown to be hard to place and susceptible to cracking a lower temperatures. Addressing these factors is an important challenge to the use of high percentages of RAP and RAS in pavement construction.
Hot-mix asphalt production is the most common paving approach in the United States; however, concerns about the process's environmental pollution continue to grow because of the emission of greenhouse gases during the construction of hot-mix pavement. To address these concerns, a new group of technologies has been developed for asphalt pavement production. These technologies, called warm mix asphalt (WMA), allow producers of asphalt pavement material to lower the temperatures at which the material is mixed and placed on the road. Reductions of 50° F. to 100° F. have been observed. Reducing production temperature results in reduced fuel consumption as well as reduced greenhouse emissions, and improves job site conditions for workers. Lower production temperature also reduces the initial aging of the binder, which can improve long-term durability and pavement performance. To produce WMA, several different technologies and additives have been used along with asphalt binder to reduce viscosity of the binder. However, most of these additives are petroleum-based and costly.
Despite the large market for scrap tires, roughly a quarter of all scrap tires end up in landfills each year numbering to approximately 27 million tires or roughly 6 million tons annually making up over 12% of all solid waste. Due to cross-linking between the rubber polymer chains, numerous additives, and stabilizers within its structure, rubber is extremely resistant to natural degradation making it troublesome for landfill storage. Crumb rubber's use in asphalt binder and pavements provides an environmentally sustainable method for disposing the millions of tires generated annually. Generally, tires are ground using ambient or cryogenic means, the goal of which is to reduce the size of the rubber into a fine powder of particle sizes smaller than 2 mm in diameter. The rubber can be used in a variety of uses, including a modifier for petroleum-based asphalt binder. The modification of asphalt mixture with rubber is typically classified into three different methods: (a) Dry Process, which uses crumb rubber as an aggregate substitute; (b) Wet Process with Agitation, in which large particles (particles not passing No. 50 Sieve) are blended with the binder while applying agitation during mixing to keep crumb rubber particles uniformly distributed; and (c) Wet Process with no Agitation, in which small particles (passing No. 50 Sieve) are blended with asphalt binder with no agitation.
One important variable in asphalt concrete pavements is adhesion between aggregate and asphalt/bitumen. Adhesion promoters, also known as anti-strips, are used to improve the interaction between asphalt and the aggregates comprising asphalt concrete. Changes to the use of asphalt concrete pavements and advances in technology have led to an increased need for adhesion promoters of particular characteristics. In particular, users are looking for asphalt pavements having longer lifespans, but over which the pavements will be subjected to increasing traffic loads. Adhesion promoters are used for a variety of goals, including by not limited to mitigating and inhibiting the damaging effects of moisture in asphalt pavements. Water damage is manifest in a number of ways, which can lead to potholes, for example, freeze-thaw cycles exacerbate the effect of water damage. On the molecular level the result of water damage is the loss of adhesion between the binder and the aggregate, also known as stripping. The majority of current adhesion promoters are petroleum-based and suffer from increasing demand and correspondingly cost, while supplies are shrinking. A source of non-petroleum based adhesion promoters is needed in the industry.
Asphalt rejuvenators are generally used to restore the balance between maltenes and asphaltenes in asphalt binder that has been disturbed over time due to progressive aging. Because of weathering or oxidation, the ratio of maltenes to asphaltenes is changed as some of the maltenes compounds are transformed to asphaltenes component over time. The effectiveness of a rejuvenator is typically evaluated by whether it can restore the maltene/asphaltene balance; targeted rejuvenators usually contain maltenes-type fractions to improve and balance the maltenes to asphaltenes ratio. To evaluate its effectiveness as a rejuvenator a test method, including but not limited to asphalt penetration, viscosity, or abrasion loss test are used.
Asphalt rejuvenators are usually formulated to revive an aging pavement, improving the composition of the asphalt cement and increase penetration value of the asphalt cement in the top portion of the pavement thereby increasing the durability and lifespan of the pavement and to seal pavement against air and water, thereby slowing oxidative degradation. Typically, rejuvenators are used on asphalt pavement to stop and/or reverse shrinking which can lead to hairline cracking, to inhibit pitting and raveling, and to reduce air and water permeability, which can lead to pavement degradation. Asphalt rejuvenators can be used in asphalt rehabilitation as well as hot-in place and cold-in place recycling.
Asphalt extenders are generally petroleum-based products enabling the recycling of asphalt waste, such as RAP, RAS, as well as natural asphalt sources such as rock asphalt, tar sands, Gilsonite, and Trinidad Lake Asphalt. Asphalt extenders enable a larger amount of asphalt waste material to be used in a performance grade asphalt mix, thereby reducing the cost of the performance grade asphalt mix having the targeted mechanical and physical properties. Alternate sources of asphalt extenders are needed in the industry, particular as petroleum sources become ever more expensive and continue to raise environmental concerns.
The above-identified needs in the asphalt industry have motivated several unsuccessful attempts by researchers to produce bio-asphalt from various materials (sugar, molasses, potato starches, vegetable oils, lignin, cellulose, palm oil waste, coconut waste, and dried sewage). However, those bio-asphalts either found not to be feasible or never reached the asphalt market due to low performance or high production cost.
Thus, there remains a need for non-petroleum based asphalt that can be used in pavement construction. In particular, there is a need for asphalt bio-binders, bio-adhesion promoters, asphalt bio-rejuvenators, asphalt bio-extenders as well as bio-asphalt. In addition, there is a need for bio-adhesives that can be used roofing, soil stabilization, crack and joint sealing and as flooring adhesives.